Field of the Invention
The invention relates in general to a touch device, and more particularly, to a single layered electrode structure of a touch device.
Description of the Related Art
Touch panels make a large scale industry. Various electronic products adopt touch panels as critical input/output devices for human-machine interfaces. The performance of touch panels depends on sensing electrodes and logic circuits connected thereto. Thus, the design and quality of the sensing electrodes dominates the performance of touch panels.
The sensing electrodes of a touch panel are generally formed on a transparent substrate. Light emitted from a display device penetrates the transparent substrate to reach a user. These sensing electrodes formed on the transparent substrate include multiple electrodes, which are connected to the logic circuits via multiple conducting wires.
With the compact trend of modern electronic products, the thickness of touch panels has become the critical factor of the thickness of touch screens. Further, multi-touch has become a fundamental function of human-machine interfaces. Thus, single layered and multi-point projected capacitive touch panels are currently one of the few touch panel forms that satisfy all of the above requirements.
With the constant increase resolution demand of display devices, the performance requirements of touch panels also become higher. To provide better performances including the resolution, precision, sensing speed for fast-moving objects for touch devices, more electrodes and conducting wires need to be fit into a limited touch area.
Projected capacitance touch sensing technique senses a capacitance value Cm between a driving electrode and a sensing electrode when an external conductive object, e.g., a finger or a stylus, approaches or comes into contact with (to be referred to as coming into a proximity of) a touch panel. By detecting a total capacitance change, positions of coordinates of more than one proximity events can be learned. However, in addition to the capacitance value Cm between the driving electrode and the sensing electrode, the external conductive object is also affected by a capacitance value Cd between the external conductive object and the driving electrode, a capacitance value Cs between the external conductive object and the sensing electrode, and a capacitance value Cf between the external conductive object and a ground voltage. Especially in a touch area that is becoming more and more crowded as greater numbers of driving electrodes and sensing electrodes need to be fit therein, reducing the capacitance value Cd and the capacitance value Cs may be extremely challenging.